1. Field of the Invention
The present invention relates to an endoscopic-use treatment instrument inserted into an operation channel of an endoscope apparatus.
2. Background Art
Endoscopic Submucosal Dissection (ESD) is a commonly known living-mucosal-tissue resection method using an endoscope including: fully incising a normal mucosa developed outside relative to an affected site developed on the surface of gastrointestinal tract, removing a submucosa; and resecting the affected site.
In a manipulation associated with the aforementioned method, an endoscopic-use treatment instrument uses various treatment mechanisms provided to the distal end of a wire inserted into an operation channel of an endoscope and projected from the distal end of the endoscope (for example, see Patent Document 1). In some cases, the treatment instrument needs to rotate a distal end mechanism to obtain more desirable correlation between an treatment object tissue and the distal end mechanism.    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. S57-145654
In case of rotating the distal end mechanism, a user rotates a proximal operation section having the proximal end of a wire fixed thereto to apply rotational torque to the distal end mechanism. However, the distal end mechanism hardly rotates if the distal end mechanism has a shape expanding outward in a radial direction in the exterior of the sheath 111 having a wire 110 passing therethrough as shown in FIG. 9 and makes friction force upon making contact with the inner surface of a sheath 111 and with an insulative member 113 fixed in the sheath 111.
The distal end mechanism in this case makes not a gradual rotation based on applied torque but so called intermittent rotation in which rotation occurs when the applied torque exceeds a predetermined value. The occurrence of intermittent rotation is problematic because it is difficult to position the distal end mechanism relative to an object tissue based on irregular correlation between rotational manipulation and the rotation amount of the distal end mechanism.